1. Field of the Invention
This invention relates to liner elements for rotary piston machines comprising at least one rotor having a plurality of apices and projecting seals at the apices which engage a trochoidal shaped surface in a housing in which the rotor rotates. Such machines include both engines such as Wankel type engines, compressors and pumps having one or more cavities containing rotors rotatable about a common or parallel axes.
2. Description of the Prior Art
U.K. Patent Specification No. 954,750 describes a housing for a rotary piston machine having an elliptical bore into which a bush having an elliptical external surface and a trochoidal inner surface. The forming of the trochoidal surface on a separate bush is intended to overcome certain difficulties said to arise in spraying a suitable wear resistant metal onto a trochoidal surface formed on the bore of the housing itself. However the machining of a trochoidal surface in the bush to be inserted in a bore in the housing or in the housing itself is a difficult operation which requires special machines which are extremely costly. The present invention therefore seeks to provide a liner for the bore of the housing of a rotary piston machine having a trochoidal surface which can be formed by relatively simple operations which avoid the necessity of machining a trochoidal surface.